I've passed on the details of Thames Rib Experiance and said they come recommended.
The Lady concerned used to work for me in my previous career, the non marine industry one that actually paid well
She and some colleagues have booked a team building day in London doing various things all arranged by an event management company.
She often still runs stuff by me to see if they stack up, and when I saw the cost of two hours on the river for 12 people I suggested she could do better booking that bit herself.
I've often thought of trying to get into event management myself, and judging by what she would have been charged I think I'll look at it again.